Place pork, sherry and ginger slice in a 2-quart pan. Cut 1 of the scallions in half crosswise and add to pork, then add enough water to barely cover meat. Bring to a simmer; cover and simmer until meat is tender when pierced (about 45 minutes). Lift meat from broth and refrigerate until cold.

Cut meat into 1 1/2-inch square pieces about 1/8 inch thick. In a bowl, combine hot bean sauce (or red chiles), sweet bean sauce, soy sauce and sugar. Seed bell peppers and cut into 1 inch squares; cut remaining 2 scallions into 1-inch lengths. Place a wok over high heat; when wok is hot, add 2 tablespoons of the oil. When oil is hot, add bell peppers and stir fry for 1 1/2 minutes, adding a few drops of water if wok appears dry. Sprinkle with salt and stir once, then remove peppers from wok. Add remaining 1 tablespoon oil to wok. When oil begins to heat, add garlic and minced ginger and stir once; then add pork and stir-fry for 1 minute. Add bean sauce mixture and toss until pork is coated with sauce. Return bell peppers to wok along with onion. Stir for 30 seconds to heat through.